Haru Ichinose is a student at a private girls’ boarding school, Myōjō Academy, who is being targeted by 12 assassins disguised as students. Tokaku Azuma is a transfer student and an assassin who also initially targets Haru, but eventually develops feelings for her and decides to protect her from the other assassins.
Akuma no Riddle Episode Synopsis
Episode 1: The World is Full of ___
A skilled assassin named Tokaku Azuma is transferred into Myōjō Academy’s ‘Black Class’, tasked with identifying and killing a target amongst her twelve classmates, the rest of whom are also assassins. At her first homeroom class, consisting of five of the total 13 students, Tokaku finds herself drawn towards a kindly girl named Haru Ichinose, believing she may be the target. As Tokaku spends more time with Haru, who is revealed to be her roommate, she notices some knife wounds on her legs. After encountering her various classmates throughout the evening, Tokaku, who had also been tasked by her master, Kaiba, with solving a puzzle reading “The world is filled with (___)”, becomes bewildered when Haru suggests ‘forgiveness’ as an answer.
Episode 2: What Dwells In Your Heart?
Tokaku is surprised when Kaiba replies that ‘forgiveness’ is the correct answer to his riddle. The next school day, as more students join the Black Class, Haru decides to have lunch with Tokaku, whilst the other students hear from Nio Hashiri about a meeting concerning their mission. Later that day, classmate Isuke Inukai comes around to have tea with Haru, slipping her a sleeping drug with the intent of drowning her in a bath whilst she is asleep. When Tokaku learns from Haruki Sagae that Isuke is targeting Haru, she rushes back to her room to stop Isuke, fighting against her to protect Haru. Isuke overwhelms her after Tokaku becomes hesitant to kill her, but decides to take her leave. After Tokaku regains consciousness, Haru, who was actually aware of what was happening and knows she is being targeted, asks her why she came to her rescue, stating her determination to graduate from Black Class alive to honor her family who died protecting her. That night, a meeting is held amongst the other assassins where they are briefed on their mission. Each assassin is given one opportunity to assassinate Haru, and whoever kills Haru first will have any wish they desire granted, with those who fail their assassinations within 48 hours of giving an advanced warning becoming expelled. Upon arriving at the meeting, Tokaku announces that she has defected to Haru’s side and will be her protector.
Episode 3: What’s Red, But Isn’t Red?
With the higher ups approving of Tokaku’s role as Haru’s protector, the meeting comes to a close. The next day, Haru receives an advance warning that her life is being targeted and decides not to inform Tokaku, becoming determined to defend herself. Later, as the Black Class visits a botanical garden, Haru is befriended by Otoya Takechi, unaware that she is the one who sent the warning. Later that night, Tokaku warns Haru not to be so naive and explains the rules concerning her assassination, but Haru states her hope that the other assassins could legitimately become her friends and noone will have to die. The next day, Otoya uses an opportunity to get close to Haru and knock her out with some neurotoxin carrying flowers, before trapping Tokaku in a boiler room so she cannot interfere. Tokaku manages to escape and learns from the others that Otoya, who is revealed to be a serial killer who gets sexual pleasure from killing her victims, is the one who sent the notice. As Tokaku manages to reach their location and fight against Otoya, she is almost killed but is saved when Haru uses the same flowers to knock Otoya unconscious. With her 48 hour time limit up come the next morning, Otoya is ‘transferred’ out of the Black Class by the group’s ringleader, Nio Hashiri.
Episode 4: What Comes Suddenly and Never Leaves?
As Class Black undergo mid-term exams, Tokaku and Haru hear from Chitaru Namatame, who is often seen with Hitsugi Kirigaya, that she is not targeting Haru, as she joined the Class Black for a different reason, before later hearing an urban legend from Nio about a hidden room in the library. Upon returning to their room, Tokaku and Haru discover another advance warning, also discovering some bombs has been planted in their freezer. The culprit this time around is Kōko Kaminaga, an assassin specialising in explosives who was exiled from her organisation after her teacher was killed in a failed bombing attempt, which Kaminaga herself was responsible for, as she had set the timing that the bomb would go off at too early, which killed her teacher, instead of their target. Despite knowing the danger, Tokaku accompanies Haru to the library and manages to locate the hidden room from Nio’s rumors. There, Tokaku narrowly manages to protect Haru from a hidden bomb and pursues Kōko, who wanted to use her wish to quit being an assassin, managing to disarm her and stop her attempt, leading her to be transferred out of Class Black the next day.
Episode 5: What Do You Need in Order to Let a Caged Bird Free?
After recalling about her past with her family, she receives another riddle from Kaiba. Meanwhile, Class Black is tasked with putting on a performance of Romeo and Juliet for the academy’s culture festival, with Chitaru and Hitsugi playing the lead roles. As the classmates work on the play together, Tokaku becomes irritated by Haruki Sagae’s harsh words towards Haru during bathtime. The next evening, Haruki, who desires to have her family provided for, calls out Haru to the gym, where the play is being held, and attempts to kill her with piano wire, only for Tokaku to arrive in the nick of time. As Tokaku gets the upper hand in battle, Haruki, having confirmed with Nio that her family would be provided for even if she died in the process, triggers a trap that causes the lighting structures to come down on top of them. Tokaku barely manages to rescue Haru in time whilst Haruki, having barely survived herself, accepts her defeat and is transferred out of Class Black.
Episode 6: Beautiful Flowers Have Their ___
As the culture festival begins, Chitaru mentions to Hitsugi about how she is searching for a killer known as Angel’s Trumpet who specializes in poison, to which Hitsugi offers to help her out. Later that night, Hitsugi comes across Shiena Kenmochi, who was planning to deliver a warning to Haru, and sprays her with poison before delivering her own warning to Haru when she and Tokaku comes across the scene. The next day, as Shiena is transferred out of Class Black due to her hospitalization, the play gets underway, with Tokaku and Haru discovering many of the prop swords have been covered in poison. Spotting this, Chitaru suspects that Haru is Angel’s Trumpet, the one who killed her teacher’s daughter, and faces against Tokaku in an off-stage sword fight. During the battle, Hitsugi comes forward and confesses that she herself is Angel’s Trumpet. Returning to the play, Hitsugi allows herself to be stabbed by Chitaru, who then learns from Nio that her wish was to leave with her once everything was over. Feeling remorse, Chitaru drinks the remainder of Hitsugi’s poison and falls alongside her, with the audience unaware.
Episode 7: What Can Never Be Caught Up To?
As Class Black prepares to go to the school’s pool, Suzu Shutō straps a bomb around Haru’s neck, set to explode at midnight. In order to disable it, Tokaku is tasked with finding four cards that make up a 4-digit password required to unlock the bomb, of which she is only allowed three tries. Tokaku finds the first card, a seven of diamonds, inside a watermelon, but loses her first password attempt whilst testing out a theory that the other digits are the sevens taken out of the deck they came from. Tokaku finds the second card, a joker for zero, on a searchlight, and finds the third hidden in the deck itself. Meanwhile, after Ataru shows up to congratulate Suzu on her birthday, Suzu explains to the others that she has a condition that prevents her body from aging, which led to a man she admired coming to outage and leave her, and her wish is to be able to age normally and eventually die. With less than fifteen minutes til minute, Tokaku rides in the flume in search for the fourth card, but becomes trapped inside a cage which sinks to the bottom, giving the choice of either saving Haru or herself. Haru then kisses Tokaku, which awakes Tokaku, who then witnesses Haru saving her, leaving them with only three digits to guess the password from. Tokaku presumes from Ataru’s announcement that the password is likely to be Suzu’s birthday, whilst Haru deduces that the actual date is that of the man she admired, managing to disarm the bomb at the last second. Accepting her loss, Suzu takes her leave from Class Black.
Episode 8: Which Gatekeeper is the One Who Lies?
While Isuke contacts her mother, who trained her to become an assassin, Nio meets up with the school’s chairman, Yuri, to discuss Class Black’s current situation, learning that a typhoon is approaching. Meanwhile, Tokaku and Haru are approached by Shinya, the split personality of Mahiru Banba who appears during the night, leading Tokaku to believe that she will be the next one to target Haru. The next day, as Tokaku wonders what she will do when Class Black is over, she and Haru discover an advance warning, which appears to be from Mahiru/Shinya, and rush back to their dorms. However, they are confronted by Isuke, the real owner of the warning, who injures Tokaku’s arm. Tokaku takes Haru to the biology room, telling her to hide there whilst she goes to confront Isuke, who calls Tokaku’s bluff that she is actually unable to kill anyone. With Tokaku distracted by her fight against Isuke, Shinya appears before Haru, declaring her intent to kill her.
Episode 9: What Dwells In Your Heart? (Make-up Test)
It is shown that Tokaku’s inability to kill came from her aunt, who followed her sister’s wishes to not have Tokaku grow up to a killer like the rest of her bloodline. With Tokaku still locked in battle with Isuke, Haru attempts to escape from Shinya’s violent mallet attacks on her own esteem. After receiving another message from Kaiba, Tokaku manages to stun Isuke with a taser hidden in her shoe and escape. However, she falls into a trap laid out by Isuke and is pushed off a bridge. Meanwhile, Haru is chased to the A/V room of the school, where Isuke uses a projector’s light to cause Shinya to experience traumatic memories and knocks her out before turning her attention towards Haru. Tokaku, who had managed to survive her fall, finally comes to understands how her mother and aunt protected her with their lives and overcomes her hesitation, stopping Isuke and rescuing Haru. With both Isuke and Shinya defeated, the remaining classmate, Sumireko Hanabusa, prepares to make her move.
Episode 10: Who Is The Queen?
With only Tokaku, Haru, Nio, and Sumireko remaining in Class Black, Sumireko gives Haru an invitation to a tea party, claiming it not to be an advance notice. Meanwhile, Otoya breaks out of prison and sneaks into the dorms to try and target Haru again, but is stopped by Sumireko, who crushes Otoya’s scissors in her hand with little effort. Later that night, Haru and Tokaku arrive at the tea party, where they discover robotic puppets of all the other classmates, as well as the restrained Otoya. After explaining how she wants to prove she is a stronger “queen” than Haru, Sumireko delivers her notice and has her puppets attack Tokaku, giving her a selection of guns to fight against. After being prevented from separating herself from the others to target Haru, Sumireko reveals she has powerful robotic limbs and launches a fierce attack against Haru. In the ensuing battle, Otoya breaks free and manages to disable one of Sumireko’s arms, only for her to replace it with another weapon, with Otoya once again captured by Nio. As Tokaku becomes cornered, Haru lures Sumireko away from her and uses her robotic limbs to her own advantage, knocking her off the side of a building. After receiving another text from Kaiba asking “Who is the queen?”, Tokaku asks Haru what Sumireko meant by her words about her being a “queen bee”, but Haru simply says it is not the time to tell her yet.
Episode 11: How to Distinguish a “Congratulation” from a “Curse”
With all the other assassins defeated, Nio announces there will be an orientation held at midnight revealing the secret behind Class Black, implying that Haru already knows something. That night, Tokaku and Haru arrive at the orientation, where they are greeted by Yuri, who reveals Class Black was designed as a test to see if Haru could survive against twelve assassins and become a successor for her clan, who control most of the world. Yuri implies that Haru, consciously or not, allegedly has the power to manipulate and control others into protecting her, which Haru refuses to acknowledge. As Haru runs off in denial, Yuri asks Tokaku to think of a wish she wants granted for winning Class Black. That night, as Tokaku feels she had been manipulated the entire time, with no way for Haru to prove otherwise, Kaiba tells her that all of the riddles he had sent her have no “right” answers, tasking Tokaku with finding her own answers. Meanwhile, after Haru asks Yuri to let her leave the clan and live a normal life, Nio takes her to their clan’s cemetery, which Myōjō Academy was built upon, giving her some time to reflect on things. After spending time with her family’s grave, Haru is approached by Tokaku, who delivers her own advanced warning and draws her sword against her.
Episode 12: Therefore, the World is Full of ____
As Tokaku begins her attack, Haru is suddenly dragged off by another Tokaku, who claims the other Tokaku is actually Nio using hypnotic suggestions to take on her appearance. The two Tokakus soon battle against each other with the real Tokaku managing to overcome her fake and stab her. Haru then charges against Tokaku, but ends up becoming stabbed herself, leaving Tokaku devastated, feeling the one wish she has can no longer be granted. As the end of the school year comes, it is revealed that both Haru and Nio had survived their attacks, with Haru becoming the sole graduate of Class Black. With all the other assassins returning to their regular lives, Tokaku sends one last reply to Kaiba before joining Haru in delivering everyone’s diplomas.
After the credits, Kaiba receives a text message and smiles, though the content of the message is not revealed.
Episode 13: Who’s the Winner? (Surprise Test)
Nio strands everyone in Class Black on a remote island and initiates a scramble game, in which all the other students must try to obtain a charm from Haru using weapons found on the island without losing their own charms. As the game goes on, many students are eliminated and brought to the loser’s area for a barbecue, resulting in a five-way struggle between Haru, Tokaku, and the remaining participants. In the end, Haru’s charm goes flying and ends up in the hands of Ataru, who is declared the winner of the contest.